Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M1C 1A4, Canada.
Ecol Lett. 2014 Nov;17(11):1427-36. doi: 10.1111/ele.12346. Epub 2014 Aug 28.
Despite the importance of divergent selection to the speed of evolution, it remains poorly understood if divergent selection is more prevalent in the tropics (where species richness is highest), or at high latitudes (where paleoclimate change has been most intense). We tested whether the rate of climatic-niche evolution - one proxy for divergent selection - varies with latitude for 111 pairs of bird species. Using Brownian motion and Ornsetin-Ulhenbeck models, we show that evolutionary rates along two important axes of the climatic-niche - temperature and seasonality - have been faster at higher latitudes. We then tested whether divergence of the climatic-niche was associated with evolution in traits important in ecological differentiation (body mass) and reproductive isolation (song), and found that climatic divergence is associated with faster rates in both measures. These results highlight the importance of climate-mediated divergent selection pressures in driving evolutionary divergence and reproductive isolation at high latitudes.
尽管分歧选择对进化速度很重要，但分歧选择是否更普遍存在于热带地区（物种丰富度最高）还是高纬度地区（古气候变化最剧烈），这一点仍知之甚少。我们检验了 111 对鸟类物种的气候生态位进化率——分歧选择的一个指标——是否随纬度而变化。利用布朗运动和 Ornstein-Uhlenbeck 模型，我们表明，沿气候生态位的两个重要轴——温度和季节性——的进化速率在高纬度地区更快。然后，我们检验了气候生态位的分歧是否与生态分化（体重）和生殖隔离（歌声）重要性状的进化有关，结果发现，气候的分歧与这两个方面的更快进化速度都有关。这些结果突出表明，气候介导的分歧选择压力在高纬度地区推动了进化分歧和生殖隔离。
